A friend of mine sells building-scale air purification systems in Asia and this is definitely the case. The nicest new buildings in wealthier Chinese cities hav

A friend of mine sells building-scale air purification systems in Asia and this is definitely the case. The nicest new buildings in wealthier Chinese cities have seriously heavy duty air filtration systems and are built with heavy duty windown and door seals. The urban middle class buys portable air filtration systems, it's a huge market.